Rigid Gas Permeable Contact Lenses
RGP corneal lenses have been the mainstay of Keratoconic contact lens fitting for many years. The Rose K brand of lenses have been highly successful in the therapy of the condition and were, at least, the first standardised bespoke KC lens design.
They are still very much in use today although they are not the the authors first choice, however, newer design features have made the lens fitting much more flexible and versatile. This includes the sectoral management feature which allows the lens to be adjusted in specific areas independently of the lens as a whole. This is especially useful for moderate to advance cones, for unusually placed cones and for PMD.
The lens is designed to be fitted to the steepest area of the cornea and it should not heavily bear on the apex of the cone. There is of course an inevitable amount of corneal touch and this can cause issues in long term wearers especially if the corneal shape changes rapidly. The lenses are designed to move and to translate tears underneath the lens for better nutrient and oxygen transmittance.